Congenital hypotrichosis / thymic aplasia (r)
Congenital hypotrichosis describes a condition where the kittens are born with no hair. In addition, they have thymic aplasia which leads to immune deficiency and increased risk of infection and death. The condition has an autosomal recessive inheritance.
Casal M L et al (1994) Congenital hypotrichosis with thymic aplasia in nine Birman kittens. Journal of the American Animal Hospital Association 30, 600-602
Corneal dermoid describes the anomalous presence of a portion of skin and hair on the surface of the cornea (the clear front of the eye). The condition may be unilateral or bilateral, and a familial inheritance has been suggested. The prognosis following surgical excision by keratectomy (surgery to remove the extra piece of skin) is excellent.
Hendy-Ibbs PM (1985). Familial feline epibulbar dermoids. Veterinary Record 116: 13
Congenital nuclear cataracts (opacity within the lens of the eye) have been reported in Birman kittens, but there is insufficient evidence to conclude that this is an inherited condition in this breed.
Schwink K (1985). Posterior nuclear cataracts in two Birman kittens. Feline Practice 16: 31-33
Spongiform degeneration (r)
This is a progressive degenerative disease of the central nervous system. Clinical signs included proprioceptive deficits, hind-limb weakness and ataxia (uncoordinated movement). The onset of clinical signs is usually 8 weeks to 5 months. Pathological brain lesions included foci of spongy change and vacuolation. Spinal cord lesions predominated in thoracolumbar region with areas of Wallerian degeneration. The mode of inheritance is unknown, however affected kittens were closely inbred.
Boyd B R (1992) Encephalopathy in related Birman kittens. New Zealand Veterinary Journal 40, 160
This progressive degenerative neuropathy is characterised by hypermetria (a high-stepping walk), plantigrade stance (‘dropped hocks’) and hindlimb ataxia (uncoordinated movement). The age of onset is 8-10 weeks of age. Pathological changes include loss of myelinated fibres and astrocytosis in the central nervous system and degeneration of peripheral nerves. It has only been reported in a group of ‘in-bred’ kittens and it is possibly sex-linked (as all the affected cats have been female).
Moreau P M et al (1991) Peripheral and Central Distal Axonopathy of Suspected Inherited Origin in Birman Cats. Acta Neuropathologica 82, 143-146
A number of litters of Birman kittens have been seen that tremble and shake from the time they start moving around the kittening bed at about 10 days old, get progressively worse through weaning, but then recover completely from 12 weeks onwards. Affected kittens need to be held still so they can eat effectively. The cause is unknown and no treatment is needed.
Congenital portosystemic shunt
There is anecdotal evidence that Birman cats may be predisposed to a vascular anomaly by which the blood from the intestines bypasses the liver, a so called portosystemic shunt. They may therefore develop signs of hepatic encephalopathy caused by the systemic accumulation of ammonia, and numerous other neurotoxins. Most affected kittens have clinical signs from ~10-12 weeks of age, typically presenting with intermittent visual disturbances, pupillary dilation, ataxia (uncoordinated walking), behavioural changes (eg. aggression), seizures, lethargy, depression, and ptyalism (excessive salivation). Some kittens may have stunted growth. There is rarely any clear relationship between clinical signs and recent feeding. Diagnosis is made on finding raised bile acids in the blood and visualising the shunting vessel with ultrasound or contrast radiography. Medical and/or surgical treatment options are available.
Raised urea/creatinine concentrations (*) – early renal failure (r)
Many young Birman cats are found to have unexpectedly increased urea and/or creatinine concentrations in their blood, indicating possible kidney dysfunction. Occasionally, young Birman cats (<2 years of age) develop renal failure, with clinical signs developing shortly after routine neutering. A prospective survey of healthy Birman cats found that ~80% of cats <6 months of age had blood creatinine concentrations above the reference range, while only 35% of the adults had raised creatinine concentrations. The reason(s) for this finding remain unclear. While it could reflect sub-clinical renal (kidney) disease, the vast majority of affected cats do not go on to develop renal failure at a young age. It therefore seems appropriate to suggest that evidence of azotaemia (raised creatinine concentrations) in an otherwise healthy Birman cat should not be over-interpreted as evidence of severe or progressive renal disease. It would however, seem sensible to monitor affected cats, to perform additional tests of renal function (serum urea levels, urine specific gravity and urine protein to creatinine ratio), and to consider the possibility of renal dysfunction when undertaking anaesthesia, surgery or treatment with drugs that can potentially harm kidneys in cats of this breed.
Gunn-Moore, D A, Dodkin, S.J. & Sparkes, A.H. An unexpected high prevalence of azotaemia in Birman cats. (2002) Journal of Feline Medicine and Surgery 4, 165 – 166 (letter)
Bleeding Disorder; Factor IX deficiency, Haemophilia B or Christmas disease (r) – see general section
Atypical granulation of neutrophils (r)
Affected cats have fine eosinophilic granules present within the cytoplasm of neutrophils, however this does not appear to affect the normal function of the neutrophil. Affected cats are clinically healthy. The condition is inherited as an autosomal recessive trait
Hirch V M & Cunningham T A (1984) Hereditary anomaly of neutrophil granulation in Birman cats. American Journal of Veterinary Research 45, 2170 – 2174
Thymic aplasia (r)
A small number of kittens have been reported with complete hairlessness in combination with absence of the thymus gland and depletion of lymphocytes in other lymphoid organs, which results in immune-deficiency. An autosomal recessive mode of inheritance is suggested.
Casal ML, Straumann U, Sigg C, Arnold S, Rusch P (1994) Congenital hypotrichosis with thymic aplasia in nine Birman kittens. Journal of American Animal Hospital association 30(6): 600-602
Pelger-Huet anolomy (r)
Pelger-Huet anolomy describes an interruption of nuclear maturation of white blood cells resulting in a failure of segmentation occurring. Neutrophils are therefore hyposegmented with an immaturely shaped nucleus and coarse chromatin and eosinophils may also appear as bands. It appears to be an autosomal dominant trait. Heterozygotes are clinically well although leucocyte abnormalities may be present. Homozygotes may die in utero or early in life.
Latimer KS Rakich PM, Thomson DG (1985) Pelger-Huet anomaly in cats (case report) Veterinary Pathology 22, 370 – 374
Latimer KS, Rowland GN, Mahaffey MB (1988) Homozygous Pelger-Huet anomaly and chondrodysplasia in a stillborn kitten. Veterinary Pathology 24 (4): 325-8
Kociba GJ (2000) Leucocyte changes in disease: Pelger-Huet anomaly. Textbook of Veterinary Internal Medicine
Predisposition to FIP - see general section click here...